I completely understand how you feel. I’ve had several good jobs where having ADHD literally cost me my job no matter how hard I tried. At the time, I hadn’t been diagnosed so the level of anxiety and frustration at work was through the roof as I tried to be hyper aware of all my mistakes, which ended up with me just making more and, in some cases, even worse mistakes. Had I actually been diagnosed at the time, been medicated, and had some support from my boss, I believe I could have been incredibly successful, but no, I felt like a failure who was betrayed by their boss.
Absolutely the best possible thing you could have done was get a lawyer involved. The general population doesn’t understand this disability because it’s not visible to them (like missing a hand) and then when a mistake happens, they just think we’re incompetent or idiots. They don’t truly understand what it’s like to have 10 people talking to them all at once or the sudden irritability when they are engaged in a conversation. Or the constant anxiety about everything. Or an impulse so strong to do something that it feels like you’ll literally explode if you don’t do it.
We can explain it, but unless they have it, it will never make sense, therefore, they lack any understanding in relation to our lives. This disability may have been a boon as a hunter gatherer where being hyper-focused on a task (hunting and not dying as an example) may have made one more successful, but we don’t have to worry about our salads eating us anymore.
Props to you for having the courage to stand up for yourself and telling them to btfo.